The onset of autumn is welcomed by many New Yorkers. This summer’s triple-digit temperatures set records and sent citizens scrambling for air-conditioned spaces, pools, parks—and in some cases, hospitals.

With its scorching intensity, the summer of 2010 recalled an equally sweltering August from another century. The heat wave of 1896 was not merely a sweat-inducing inconvenience, however; it was a full-blown catastrophe. Running from August 4 to August 15, it overwhelmed the city’s infrastructure, paralyzed its leaders, and left nearly 1,500 New Yorkers dead and thousands more incapacitated. This calamity, one of the deadliest, though least-remembered, natural disasters in U.S. history, is chronicled in Edward P. Kohn’s Hot Time in the Old Town.

But Kohn’s book covers far more than meteorological history. A history professor at Ankara’s Bilkent University, Kohn meshes the heat wave with the presidential election of 1896 to suggest that the oppressive weather doomed the candidacy of Democratic nominee William Jennings Bryan and shaped the crusading populism of then–New York City police commissioner and future president Theodore Roosevelt. It’s a novel hypothesis and a fascinating story.

In July, at the 1896 Democratic National Convention, Bryan delivered his “Cross of Gold” speech—one of the most famous pieces of political rhetoric in American history. This fire-and-brimstone condemnation of the gold standard, and the bankers and lenders who supported it, incited the gathered throngs at the Chicago Coliseum into a near-riot of support and catapulted the 36-year-old Nebraskan to the party’s presidential nomination. Not everyone (including some Democrats) shared the convention-goers’ enthusiasm for Bryan’s hellfire populism. Hitching his star to an inflation-inducing, bimetallic monetary policy—which advocated free coinage of silver—he embraced the farmers and laborers of the West and vilified the “moneyed interests” of the East. Such full-throated class war made many uneasy with the prospect of a Bryan presidency.

Aware of this apprehension, Bryan, in a preview of modern presidential campaigns, took to the road. While his opponent, Republican William McKinley, remained at home in Canton, Ohio, Bryan would travel by train from his home in Lincoln to New York. Along the way, he would cross the Midwest and whip up the faithful; once in “enemy territory” (his politically miscalculated description of the East Coast), the Boy Orator, with his unmatched powers of persuasion, would take the free-silver fight to the nation’s financial capital and deliver a speech at Madison Square Garden.

Unfortunately for Bryan, the would-be triumphant tour coincided with a devastating heat wave. As the Democratic candidate rolled out of Nebraska in early August, temperatures on the East Coast started to soar. Though the suffering was national, nowhere was it greater than in New York. Ninety-degree temperatures were accompanied by 90 percent humidity. Nighttime temperatures refused to drop. There were no cooling breezes. The heat turned the city, with its asphalt, garbage-littered streets and crowded tenements, into a foul furnace.

Kohn paints a horrifying picture of a pre-air-conditioned metropolis in literal and figurative meltdown. The poor suffocated in their packed homes. The city’s workforce, toiling in the sun, succumbed to heat exhaustion. Infants and the elderly were felled in their rockers and rocking chairs. Ambulances and coroners’ wagons jammed the city’s arteries. Horses dropped like flies, their stinking carcasses left to rot in the streets, while rabid dogs, driven mad by the heat, ran wild.

In the middle of all of this was the 38-year-old commissioner of police, Theodore Roosevelt. Though eyeing a spot in Washington as part of a potential McKinley administration, Roosevelt threw himself into his duties with typical enthusiasm. Since taking office in 1895, he had aggressively enforced an unpopular and widely disobeyed Sunday ban on liquor sales, and he spent nights walking his officers’ beats to evaluate their conduct and performance.

As the heat wave descended on New York, Bryan, anticipating glory, sped east while Roosevelt took to the streets to find some solution to the city’s suffering. On his path through the Midwest, Bryan gave roaring speech after roaring speech to adoring fans in the summer sun. By the time he reached New York he was exhausted, his voice hoarse and worn. With only a day to recuperate, he took the stage at the Garden on August 12 to a packed, steamy house. Those expecting the provocative rhetorical heights of the “Cross of Gold” speech were disappointed. A beleaguered Bryan delivered a lengthy, tepid, defensive speech that in modern parlance would be considered a shift to the political middle ground. Mere minutes into his speech, a combination of boredom and the 97-degree heat drove portions of the crowd to the exits.

Notably absent was Roosevelt. Though he arranged police management of the event, the commissioner spent the evening at his Long Island home, Sagamore Hill. Though his den on Oyster Bay offered relief, Roosevelt had experienced the heat wave—and seen the destruction left in its wake—firsthand. While government officials were unable or unwilling to take action, Roosevelt devised and implemented a plan to distribute blocks of ice to the city’s poorest neighborhoods. With his usual hands-on fervor, he then walked the streets of the Lower East Side, monitoring the plan’s effectiveness.

Roosevelt’s leadership and Bryan’s failure fuel Kohn’s denouement. In the days following Bryan’s New York appearance, papers and pundits panned the speech. “Not the Bryan of dash and fire, but a careful man, treading unknown soil,” lamented one observer. Bryan retreated to Lincoln to lick his wounds. Kohn suggests that the heat wave derailed Bryan’s much-anticipated appearance at the Garden and did permanent damage to his candidacy. Bryan went on to lose the general election to McKinley.

While the heat wave hurt Bryan, Kohn argues that it helped forge the future President Roosevelt’s crusading progressive streak, which would fully emerge after he succeeded McKinley in the White House in 1901. Kohn points to passages of Roosevelt’s 1913 memoirs that vividly recall the heat wave, showing the disaster’s impact on his ideological development. Kohn recognizes that Roosevelt inherited his sense of noblesse oblige from his father, but he claims that the events of August 1896 fostered his thirst for social justice and a belief in government’s responsibility to act in times of crisis. It’s a plausible argument, though Roosevelt’s experiences here don’t seem to rise quite to the level of epiphany.

Regardless, Hot Time in the Old Town is a worthy read. By capturing the intersection of a forgotten but devastating American catastrophe, the quick rise and sudden fall of one of America’s most meteoric political figures, and a snapshot of the embryonic Rough Rider in action, Kohn presents a fascinating triptych of American history—and a timely rejoinder to New Yorkers who think they had it bad this past summer.